Cross reference is made to allowed patent application Ser. No. 09/305,990 to Altfather et al. (hereinafter xe2x80x9cAltfatherxe2x80x9d), which is herein incorporated in its entirety for its teachings, and for which there is common assignment with the present application to the Xerox Corporation.
The present invention relates to ink jet recording devices and, more particularly, to a system for detecting the presence of an ink supply container and also for detecting when the level of ink in the container is at or below a predetermined level.
Ink jet recording devices eject ink onto a print medium such as paper in controlled patterns of closely spaced dots. To form color images, multiple groupings of ink jets are used, with each group being supplied with ink of a different color from an associated ink container.
Thermal ink jet printing systems use thermal energy selectively produced by resistors located in capillary filled ink channels near channel terminating nozzles or orifices to vaporize momentarily the ink and form bubbles on demand. Each temporary bubble expels an ink droplet and propels it toward a recording medium. The printing system may be incorporated in either a carriage type printer or a page-width type printer. A carriage type printer generally has a relatively small printhead containing the ink channels and nozzles. The printhead is usually sealingly attached to an ink supply container and the combined printhead and container form a cartridge assembly which is reciprocated to print one swath of information at a time on a stationarily held recording medium, such as paper. After the swath is printed, the paper is stepped a distance equal to the height of the printed swath, so that the next printed swath will be contiguous therewith. The procedure is repeated until the entire page is printed. In contrast, the page-width printer has a stationary printhead having a length equal to or greater than the width of the paper. The paper is continually moved past the page-width printhead in a direction normal to the printhead length at a constant speed during the printing process. Moving carriage type ink jet printers must either carry the ink container along with the printhead or provide a flexible ink supply line between the moving printhead and a stationary ink container. Page-width printers have an ink supply container located outside the print zone and directly connected to the print-bar ink channels.
For either a partial width printhead on a moving carriage or for a page-width print-bar, it is desirable to have a low ink level warning to alert a user to replace or refill the ink container so that the ink does not run out during a print job. Presently, for some applications (such as plotting), some users choose to install new print containers prior to starting an extensive printing job because it is less costly to replace a questionable container rather than lose one or more colors in the output prints. It is also important to ensure that the ink supply container is in the proper location; e.g., fluidly connected to the associated printhead. In some instances, an out of ink container may be removed but a replacement container neglected to be inserted. Printer operation with the container removed could potentially damage the associated printhead.
Various prior art methods and devices are known. One that is of note here is U.S. Pat. No. 5,997,121 to Altfather et al., which discloses a low ink sensing system combined with an ink cartridge detection system to enable a more efficient ink jet printer. An ink container which supplies ink to an associated printhead is modified by the incorporation of two light directing elements, in the preferred embodiment, a faceted prism and a roof mirror, into a transparent wall of the container housing. The cartridge, comprising the ink container and associated printhead, is mounted on a scan carriage. Periodically, the carriage is conveyed to a sensing station comprising a pair of light sources and a commonly used photosensor. A first light source is energized and a beam of light is directed to a location where the roof mirror, would be positioned if the cartridge is present. If the cartridge is absent, lack of a reflected return signal is sensed, indicating a cartridge has not been inserted. Print operation is halted until a cartridge is inserted. If a cartridge is properly inserted, the roof mirror returns most of the incident light to the photosensor which generates a signal indicating the presence of the cartridge. A second light source is then energized and directed towards the faceted prism, which is either immersed in ink or exposed to air within the interior of the container. If the latter, light is internally reflected by the prism facets back to the photosensor. If a print operation has been in progress, and the ink level has fallen, the common photosensor detects either a strong or weak redirected light component and initiates a status check and generates appropriate displays of low ink level or out of ink warnings.
Also of note is U.S. Design Pat. No. 425,110 to Dietl et al. for an Ink Tank. Provided therein is the ornamental design for an ink tank, as shown and described.
Therefore, as discussed above there exists a need for a technique which will solve the problem of providing a printer which can sense it""s ink cartridge and whether that cartridge has ink inside it. Thus, it would be desirable to solve this and other deficiencies and disadvantages with an improved apparatus.
The present invention relates to an ink container comprising a housing, and a curvilinear light directing element on a wall of that housing for directing light received there away from the wall of the housing.
More particularly, the present invention relates to an ink container for use in a liquid ink printer comprising a housing defining a chamber for storing a supply of liquid ink. The invention further comprises an arched roof mirror comprising a first and a second curvilinear reflector on the exterior of a wall of the housing. The first curvilinear reflector substantially completely reflects light received there toward the second curvilinear reflector. The second curvilinear reflector substantially completely reflects light received there away from the wall of the housing on a light path offset from and parallel to the light path of the light received at the first reflector.
Further, the invention relates to a sensing system for detecting a presence of an ink container and a level of ink therein comprising a first curvilinear light directing element forming part of the ink container and a light source having output beams directed toward the first curvilinear light directing element when in an ink container detect mode. The system further comprises a first photosensor for detecting a presence or absence of light directed from the first curvilinear light directing element and for generating an output signal indicative thereof and a second curvilinear light directing element forming part of the ink container, the light source having output beams directed toward the second curvilinear light directing element when in a low ink level detect mode. Finally, the system also comprises a second photosensor for detecting light directed from the second curvilinear light directing element, the level of detected light and, hence, the level of the photosensor output being representative of a presence or absence of the ink level adjacent the interior surface of the second curvilinear light directing element.